JP4813609B2 - Deodorant using ferric hydroxide-containing water-containing neutralized sludge as production raw material and method for producing the same - Google Patents

Description

The present invention is a liquid that suppresses bad odor generated by the production of hydrogen sulfide or the like in wastewater treatment facilities or incidental facilities such as municipal sewage or factory wastewater, using ferric hydroxide-containing water-containing neutralized sludge as a production raw material. The present invention relates to a deodorant and a method for producing the same.
More specifically, in a wastewater treatment facility or ancillary facilities such as urban sewage or factory wastewater, it can be suitably used for a concentrated sludge storage facility that generates hydrogen sulfide, which is a malodorous substance, at a high concentration, etc. The present invention relates to a liquid deodorant that uses ferric hydroxide-containing water-containing neutralized sludge that is generated when neutralizing an iron compound-containing acidic aqueous solution discharged in step 1 as an iron production raw material and a method for producing the same.

  Ferrous fermented acid wastewater is generated at various steelworks, quenching factories, wire mills, and other factories or iron mines with pickling facilities. It is impossible because of the pollution and strict wastewater regulations. For this reason, the wastewater is neutralized either alone or in combination, but the produced ferric hydroxide-containing water-containing neutralized sludge is currently treated as normal waste without being particularly used.

  This waste fertilized hydroxide-containing neutralized sludge that has been disposed of has a large amount of treatment, and the disposal of hazardous materials has become very strict, making it difficult to secure a disposal site. ing. Therefore, it is desired to develop a technique for effectively reducing the amount of waste in the sludge by effectively utilizing iron in the sludge. Under such circumstances, the company to which the inventor belongs is a flocculant for sewage treatment, and manufactures and sells polyferric sulfate containing iron as a main component. The inventors of the present invention have already proposed that iron or iron compound waste is used for the production of polyferric sulfate, which is produced at a low cost and sold at a low price.

Further, from ferric ions, nitrate ions and sulfate ions produced by oxidizing ferrous ions to ferric ions in the presence of ferrous ions, sulfate ions and nitrate ions, which are iron compounds. The present inventors have found that the formed liquid composite has excellent ability to suppress the generation of hydrogen sulfide, which is one of the causes of malodors, and has already proposed it as a deodorant (Patent Document 1). .
The present inventors have already examined from this viewpoint, paying attention to the possibility of exploiting a ferric hydroxide-containing water-containing neutralized sludge.

As a result, the ferric hydroxide-containing water-containing neutralized sludge is difficult to dissolve at room temperature depending on high-concentration nitric acid (specifically, nitric acid having a concentration of 20 wt% or more), but relatively short at a temperature of 70 ° C. or more. It is possible to prepare an aqueous solution that dissolves in time, contains ferric iron in an amount of 7.1 to 17 wt% in terms of Fe ₂ O ₃ , and has a NO ₃ / Fe molar ratio in the range of 2.3 to less than 3.0. It was confirmed that it was possible to suppress the malodor caused by hydrogen sulfide generated in wastewater treatment facilities and the like, and a patent application was made and a patent was already obtained (Patent Document 2).

In order to promote the use of such deodorants with excellent performance in sewage treatment facilities, etc., when sales activities were conducted for such facilities, etc., samples were provided, it was concentrated to generate high-concentration hydrogen sulfide. In facilities that store sludge, etc., there was a feeling that the deodorizing performance was not sufficient.
Therefore, a simple deodorization performance test by humans using the deodorant of Patent Document 2 on the concentrated sludge that generates high-concentration hydrogen sulfide, that is, a human odor sensitivity test, a slight odor is felt. It was.

JP-A-11-206863 Patent No. 4,098,584 (Japanese Patent Laid-Open No. 2004-82006)

For this reason, in order to obtain objective data on the deodorizing performance of this deodorant, a deodorizing performance test was conducted using a gas detector tube on concentrated sludge that generates high-concentration hydrogen sulfide. It was found that the odor performance was not perfect as described in Patent Document 2.
In order to investigate the cause, first, the composition of the liquid deodorant was investigated, and it was found that sulfate radical (SO ₄ ) was present in a considerable amount, that is, 2.4 wt%.

Then, in order to investigate the origin of the sulfate radical, the composition of the ferric hydroxide-containing water-containing neutralized sludge as an iron raw material was analyzed, and it was found that a large quantity of sulfate radical was present. That is, it was found that the ferric hydroxide-containing water-containing neutralized sludge, which is a raw material for producing the deodorant described in Patent Document 2, contains a large amount of 13.9 wt% (dry basis) sulfate radicals.
Therefore, a considerable amount of sulfate radicals derived from ferric hydroxide-containing water-containing neutralized sludge remain in the deodorizer of Patent Document 2, and the sulfate radicals are reduced by sulfate-reducing bacteria in an anaerobic atmosphere. It was estimated that hydrogen sulfide would be generated, and the deodorization performance was improved by using a deodorizer with a low content of sulfate radicals.

Therefore, the present invention uses ferrous hydroxide-containing water-containing neutralized sludge as an iron raw material, and on the basis of the above knowledge, it is excellent for sources such as concentrated sludge that generates high-concentration hydrogen sulfide. Accordingly, it is an object of the present invention to provide a liquid deodorant exhibiting a deodorizing performance and a method for producing the same.
More specifically, the present invention is produced using ferric hydroxide-containing water-containing neutralized sludge produced when neutralizing an iron compound-containing acidic aqueous solution discharged at various metal processing plants or the like as a production raw material. In other words, it is a liquid deodorant manufactured by effectively utilizing waste, but it has excellent deodorizing performance against sources such as sludge that generate high-concentration hydrogen sulfide. It is an object of the present invention to provide an agent and a method for producing the same.

The present invention provides a liquid deodorant and a method for producing the same to achieve the above object, and the liquid deodorant is ferric hydroxide produced when an iron compound-containing acidic waste liquid is neutralized. a a water-containing sludge in a liquid deodorant which is produced as a raw material, a second iron contained 7～35Wt% in terms of Fe ₂ O _3, NO ₃ / Fe molar ratio in the range from 3.0 6.0 And an aqueous solution having a SO ₄ concentration of 1.6 wt% or less.
The liquid deodorant has a ferric content of 9 to 20 wt% in terms of Fe ₂ O ₃ , a NO ₃ / Fe molar ratio in the range of 3.5 to 5.5, and an SO ₄ concentration of 0.8. It is preferable that it is 8 wt% or less.

The manufacturing method of the liquid deodorant is a ferric-containing aqueous sludge hydroxide generated when neutralized iron compound-containing acidic waste liquid, the molar ratio of the nitric acid concentrations above 20wt% NO ₃ / Fe is It mixes in 3.0 to 6.0, and is heat-dissolved at the temperature of 60-100 degreeC for 1 to 12 hours, It is characterized by the above-mentioned.
In addition, the nitric acid concentration at that time is preferably 50 wt% or more, the temperature is 75 to 100 ° C., and the heat dissolution time is preferably 4 to 12 hours.

Since the liquid deodorant of the present invention uses ferric hydroxide-containing water-containing neutralized sludge with respect to the iron raw material that is one of the manufacturing raw materials, it effectively uses waste and contributes to the reduction. To do.
Moreover, the ferric hydroxide-containing water-containing neutralized sludge of the iron raw material used in the present invention was thought to be difficult to dissolve compared to a high concentration because of its low SO ₄ concentration. As a result, it has been found that it can be dissolved in water, and has paved the way for further effective use of waste.

And in the process of developing the present invention, the deodorizing performance of the deodorant described in Patent Document 2 is not sufficient, and while deliberately trying to improve it, It was found that the ferric hydroxide-containing water-containing neutralized sludge used contained a high concentration of SO ₄ , and sulfate radicals derived from it remained in the manufactured deodorant. The possibility of causing hydrogen sulfide is presumed, and the present invention is effective in facilities that generate high-concentration hydrogen sulfide, such as concentrated sludge, by confirming the correctness of this assumption and solving it. It provides an excellent deodorant exhibiting deodorant performance.

That is, the deodorant manufactured in Patent Document 2 contains 2.4% SO ₄ brought from ferric hydroxide-containing water-containing neutralized sludge, which is an iron raw material, and this SO ₄ is concentrated sludge. in the high anaerobic atmosphere environment (oxygen molecule also nitrate ions state does not exist in the water) is under as reservoirs, and assumed to produce hydrogen sulfide is reduced by sulfate reducing bacteria, is sO ₄ concentration The deodorant was produced using the low ferric hydroxide-containing water-containing neutralized sludge as the iron raw material, and as a result, the present invention produced a high concentration of hydrogen sulfide. Even if it is used for concentrated sludge, etc., it exhibits good deodorizing performance.

  In the following, the present invention will be described in detail with reference to modes for carrying out the invention. However, the present invention is not limited in any way by these embodiments, but is specified by the scope of claims. Not too long.

As described above, the present invention provides a liquid deodorant and a method for producing the same, and the liquid deodorant contains ferric hydroxide-containing water-containing sludge generated when an iron compound-containing acidic waste liquid is neutralized. A liquid deodorant produced as a raw material, containing ferric iron in an amount of 7 to 35 wt% in terms of Fe ₂ O ₃ , and a NO ₃ / Fe molar ratio in the range of 3.0 to 6.0, and it is characterized in that the SO ₄ concentration is an aqueous solution of less 1.6 wt%. The liquid deodorant has a ferric content of 9 to 20 wt% in terms of Fe ₂ O ₃ , a NO ₃ / Fe molar ratio in the range of 3.5 to 5.5, and an SO ₄ concentration of 0.8. It is preferable that it is 8 wt% or less.

The manufacturing method of the liquid deodorant is a ferric-containing aqueous sludge hydroxide generated when neutralized iron compound-containing acidic waste liquid as described above, the nitric acid concentrations above 20 wt% of the NO ₃ / Fe The mixture is mixed at a molar ratio of 3.0 to 6.0 and heated and dissolved at a temperature of 60 to 100 ° C. for 1 to 12 hours.
In addition, the nitric acid concentration at that time is preferably 50 wt% or more, the temperature is 75 to 100 ° C., and the heat dissolution time is preferably 4 to 12 hours.

In the liquid deodorant of the present invention, it is necessary that ferric iron is contained in an amount of 7 to 35 wt% in terms of Fe ₂ O ₃ , and if it is less than 7 wt%, the iron concentration is too low and the effect of suppressing the generation of hydrogen sulfide is reduced. This is because, when it exceeds 35 wt%, ferric nitrate crystals are precipitated. It is preferable that the content of ferric contained 9～20Wt% in terms of Fe ₂ O _3.

Furthermore, the NO ₃ / Fe molar ratio needs to be in the range of 3.0 to 6.0, which means that if the NO ₃ / Fe molar ratio is less than 3.0, the amount of iron is excessive and the solution is incomplete. This is because crystals of ferric nitrate are precipitated, and when it exceeds 6.0, the concentration of NO _{3 in} the solution becomes high and the acidity of the solution becomes too strong. Because.
The molar ratio is preferably 3.5 to 5.5.

About this molar ratio, although it is a high value compared with the liquid deodorant of patent document 2, when melt | dissolving ferric hydroxide containing water-containing sludge with nitric acid, the content rate of a sulfate radical is When it is low, it is harder to dissolve than when it is high, so that the nitric acid concentration is high and the amount of use increases in order to efficiently dissolve in a short time.
As a result, the obtained liquid deodorant has a high nitrate radical concentration and a high NO ₃ / Fe molar ratio. In addition, since it is as above-mentioned, compared with the manufacturing method of patent document 2, it is inevitable that the heating temperature at the time of melt | dissolution will become high and melt | dissolution time will also become long.

Further, in the liquid deodorant of the present invention, the SO ₄ concentration needs to be 1.6 wt% or less, and if it exceeds this, the liquid deodorant is contained in the ferric oxide-containing water-containing sludge that is an iron raw material. When SO ₄ incorporated in the odorant forms a highly anaerobic atmosphere like concentrated sludge, it is reduced by sulfate-reducing bacteria and hydrogen sulfide is likely to be produced. It is thought that it falls.

In the present invention, ferric hydroxide-containing hydrous sludge generated when neutralizing an iron compound-containing acidic waste liquid that is a waste as an iron raw material is used, and the liquid deodorant of the present invention has a concentration thereof. It is manufactured by heating and dissolving using 20 wt% or more nitric acid.
In that manufactured deodorant, SO ₄ contained therein is required to be less concentration 1.6 wt%, although the preferably not more than 0.8 wt%, the SO ₄ That is, the sulfate radical is derived from ferric hydroxide-containing water-containing sludge, which is an iron raw material, and remains in the manufactured liquid deodorant.

Therefore, the SO ₄ concentration in the ferric hydroxide-containing water-containing sludge, which is an iron raw material, is naturally limited, and is within the range where the sulfate group concentration in the deodorant obtained after dissolution can be achieved.
That is, in order to make the sulfate group concentration in the deodorant 1.6 wt% or less, the sulfate group concentration in the sludge needs to be 6.61 wt% (based on the dry basis). In order to make the sulfate radical concentration in the agent 0.8 wt% or less, the sulfate radical concentration in the sludge needs to be 3.96 wt% (based on the dry base) or less.

In the liquid deodorant of the present invention, as described above, ferric iron is contained in an amount of 7 to 35 wt% in terms of Fe ₂ O ₃ , the NO ₃ / Fe molar ratio is 3.0 to 6.0, and SO ₄ An aqueous solution having a concentration of 1.6 wt% or less is required, and in order to produce it, nitric acid having a concentration of 20 wt% or more is added to ferric hydroxide-containing water-containing sludge with a NO ₃ / Fe molar ratio of 3 It is necessary to mix at 0.0 to 6.0 and dissolve by heating at a temperature of 60 to 100 ° C. for 1 to 12 hours.

The liquid deodorant of the present invention is also common to the case of Patent Document 2 in that ferric hydroxide-containing water-containing sludge is used as an iron raw material, but is used in the method for producing a liquid deodorant of the present invention. As described above, the ferric hydroxide-containing water-containing sludge has a lower sulfate group concentration than the ferric hydroxide-containing water-containing sludge used in Patent Document 2.
As a result, as compared with the production method described in Patent Document 2, the conditions for dissolving the ferric hydroxide-containing hydrous sludge with nitric acid become severe.

Therefore, in the method for producing a liquid deodorant of the present invention, the concentration of nitric acid to be used is preferably higher than that in Patent Document 2, and specifically 50% or more is preferable.
Also, the heating temperature is preferably high and is preferably 75 ° C. or higher. Further, when the nitric acid concentration and the heating temperature are the same as in Patent Document 2, the dissolution time is preferably doubled or more, and specifically, 4 hours or more is preferable.

In the following, the present invention will be described in detail based on examples, but the present invention is not limited to these examples, and it is needless to say that the present invention is specified by the claims. .
About the Example, a several example regarding the manufacturing method of the liquid deodorant of this invention is shown as Example 1, and the deodorizing performance test example using the liquid deodorant manufactured as Example 2 is shown.

[Production Example 1]
As the ferric hydroxide-containing water-containing sludge of the iron raw material, the one discharged in the manufacturing process of the semiconductor material was used.
When the components were first analyzed, the results were as shown in Table 1. The contents of Fe ₂ O ₃ and SO ₄ contained therein were 75.4 wt% and 2.10 wt%, respectively, on a dry basis. In addition, 39 wt% of water was contained.

30 g of this ferric hydroxide-containing hydrous sludge was sufficiently suspended in 54 g of 60 wt% nitric acid so that the NO ₃ / Fe molar ratio at the time of dissolution was 3.0, and then the temperature of the suspension was changed to 80 The mixture was heated to 0 ° C., and after reaching the same temperature, stirring was continued for 4 hours. After 4 hours, the dissolved solution was cooled to 40 ° C. or lower, and the dissolved residue was separated into solid and liquid using 5C filter paper.

The filtrate, T-Fe concentration contained therein was measured NO ₃ concentration and SO ₄ concentrations. The dissolution residue separated by filtration was dried at 110 ° C., and then its weight was measured to calculate the dissolution rate of the raw material sludge. These results are as shown in Table 2, T-Fe concentration 10.6Wt% in the filtrate (Fe ₂ O ₃ reduced concentration 15.0 wt%), NO ₃ concentration 38.5%, NO ₃ / Fe molar The ratio was 3.3 and the SO ₄ concentration was 0.5%. The dissolution rate of the raw material sludge was 76%.

[Production Example 2]
Production Example 1 except that the same ferric hydroxide-containing hydrous sludge as in Production Example 1 was used and the concentration of 60 wt% nitric acid was changed to 82 g so that the NO ₃ / Fe molar ratio during dissolution was 4.5. And dissolved under the same conditions.
The results are shown in Table 2 in the same manner as in Production Example 1. The T-Fe concentration in the filtrate was 9.6 wt% (Fe ₂ O ₃ equivalent concentration 13.7 wt%), the NO ₃ concentration 43.8%, NO _{The 3} / Fe molar ratio was 4.1 and the SO ₄ concentration was 0.5%. The dissolution rate of the raw material sludge was 90%.

[Production Example 3]
Production Example 1 except that the same ferric hydroxide-containing hydrous sludge as in Production Example 1 was used and the concentration of 60 wt% nitric acid was changed to 109 g so that the NO ₃ / Fe molar ratio during dissolution was 6.0. And dissolved under the same conditions.
As a result, are shown in the same manner as in Examples 1 and 2 in Table 2, T-Fe concentration 11.6Wt% in the filtrate (Fe ₂ O ₃ reduced concentration 16.5 wt%), NO ₃ concentration 48.4% The NO ₃ / Fe molar ratio was 5.6, and the SO ₄ concentration was 0.2%. The dissolution rate of the raw material sludge was 94%.

[Production Example 4]
The ferric hydroxide-containing hydrous sludge used as an iron raw material has a relatively low sulfuric acid content discharged in the production process of semiconductor materials used in Production Examples 1 to 3 so far, and is used in Patent Document 2. Only two types of sulfate radicals produced when neutralizing and precipitating iron sulfide mine wastewater are contained at high concentrations.
Therefore, a liquid deodorant having a sulfate group content intermediate between these two cannot be produced directly by dissolving with nitric acid from ferric hydroxide-containing water-containing sludge.

Therefore, for a liquid deodorant containing a sulfate group intermediate between the two, sulfuric acid is added to the ferric hydroxide-containing water-containing sludge of Production Example 1 to increase the sulfate group, and this is dissolved in nitric acid to obtain a liquid. A deodorant was prepared and used for a deodorization performance test.
That is, sulfuric acid was added to the ferric hydroxide-containing hydrous sludge of Production Example 1, mixed and dried to increase the sulfate radical concentration, which was used as the iron raw material for producing the liquid deodorant.

The production method is specifically as follows. That is, 2.54 g of 98% sulfuric acid was added to 100 g of ferric hydroxide-containing hydrous sludge as in Production Example 1, and the mixture was sufficiently stirred and mixed and allowed to stand overnight to dry. The results of analysis of the components are shown in Table 3, and the amounts of Fe ₂ O ₃ and SO ₄ contained therein are 75.6 wt% and 3.96 wt% on a dry basis, respectively. Contained 33.3 wt% of water.

30 g of this ferric hydroxide-containing hydrous sludge was sufficiently suspended in 54 g of 60 wt% nitric acid so that the NO ₃ / Fe molar ratio at the time of dissolution was 3.0, and then the temperature of the suspension was changed to 80 The mixture was heated to 0 ° C., and after reaching the same temperature, stirring was continued for 4 hours. After 4 hours, the dissolved solution was cooled to 40 ° C. or lower, and the dissolved residue was separated into solid and liquid using 5C filter paper.
The results are shown in Table 2 together with Production Examples 1 to 3, and the T-Fe concentration in the filtrate is 10.7 wt% (Fe ₂ O ₃ equivalent concentration is 15.3 wt%), and the NO ₃ concentration is 39.8%. The NO ₃ / Fe molar ratio was 3.4 and the SO ₄ concentration was 0.8%.

[Production Example 5]
In this production example, a liquid deodorant was produced in the same manner as in Production Example 4. That is, 7.54 g of 98% sulfuric acid was added to 100 g of the ferric hydroxide-containing hydrous sludge as in Production Example 4, and the mixture was sufficiently stirred and mixed and allowed to stand overnight to dry. The components were analyzed as shown in Table 3, and the amounts of Fe ₂ O ₃ and SO ₄ contained therein were 74.4 wt% and 6.61 wt% on a dry basis, respectively. 32.5 wt% of water was contained.

30 g of this ferric hydroxide-containing hydrous sludge was sufficiently suspended in 54 g of 60 wt% nitric acid so that the NO ₃ / Fe molar ratio at the time of dissolution was 3.0, and then the temperature of the suspension was changed to 80 The mixture was heated to 0 ° C., and after reaching the same temperature, stirring was continued for 4 hours. After 4 hours, the dissolved solution was cooled to 40 ° C. or lower, and the dissolved residue was separated into solid and liquid using 5C filter paper.
As a result, the T-Fe concentration in the filtrate was 11.0 wt% (Fe ₂ O ₃ equivalent concentration 15.7 wt%), the NO ₃ concentration 40.2%, the NO ₃ / Fe molar ratio 3.3, the SO ₄ concentration 1 It was 6%.

[Considerations on Manufacturing Examples]
Comparing Production Examples 1 to 3, it can be seen that the amount of ferric hydroxide-containing water-containing sludge increases as the amount of nitric acid used during heating and dissolution increases.
That is, the amount of nitric acid used is 54 g in Production Example 1, 82 g in Production Example 2, and 109 g in Production Example 3 with respect to the same amount (30 g) of ferric hydroxide-containing hydrous sludge. The dissolution amount of the sludge also increased to 76%, 90% and 94%, and it can be seen that the iron content in the sludge is effectively utilized as a liquid deodorant.

  In this example, an example in which a deodorizing performance test is performed using the liquid deodorant produced in Example 1 as described above is shown. In this deodorization performance test, the liquid deodorizers of Production Examples 3, 4, and 5, and the deodorizer described in Patent Document 2 and a commercially available ferric nitrate solution (hereinafter referred to as a reference example). ) Was used. That is, deodorizers having a sulfate radical content of 0%, 0.2%, 0.8%, 1.6%, and 2.4% were used. In addition, the deodorant performance test was done also about the case of no deodorant addition (blank) for the comparison.

In addition, the deodorant using a commercially available ferric nitrate solution is for obtaining a deodorization performance result when using a deodorant when the sulfate group content is 0%. Using a ferric nitrate solution commercially available from Jujo Synthetic Chemical Laboratory, the components were analyzed to confirm that the sulfate group content was zero.
It was also analyzed and confirmed that the T-Fe concentration was 9.5 wt (Fe ₂ O ₃ equivalent concentration 13.5 wt%),%, the NO ₃ concentration 31.8%, and the NO ₃ / Fe molar ratio 3.0. .

In this deodorization performance test, the sludge provided by the local government was left outdoors for 10 days, after which the deodorization performance test was conducted. This is because hydrogen sulfide is likely to be generated, and as a result, the difference in the deodorizing performance of the liquid deodorant based on the difference in sulfate group concentration is considered to be clearer.
The deodorizing performance test method will be specifically described below.

Prepare 500 mL plastic bottles corresponding to the number of liquid deodorants at each sulfate concentration and the number of measurements, collect 200 mL of sludge in each plastic bottle, and add liquid deodorants at each sulfate concentration to each plastic bottle. Each was added individually so that the addition amount was 5000 ppm.
After adding the liquid deodorant, the plastic bottle was sealed and allowed to stand. Then, immediately after the addition, after standing for 6 hours and after standing for 24 hours, each bottle was shaken for 1 minute, and the hydrogen sulfide concentration in each bottle was measured with a gas detector tube.

The performance test results are as shown in Table 4. In the case of no addition of a liquid deodorant (blank), there is no significant change after the lapse of 0 to 24 hours, and in any case it exceeds 1100 ppm. .
On the other hand, when the liquid deodorant of this invention is used, it turns out that the amount of hydrogen sulfide generation is reducing extremely compared with the case of a blank. That is, it can be seen that when the liquid deodorant of the present invention is used, it is halved immediately after the addition and decreases to about 1/10 after 24 hours.

Furthermore, specifically, when the amount of hydrogen sulfide generated after 24 hours has elapsed, it is 95 pm in the case of a liquid deodorant having a sulfate radical concentration of 0.2%, 110 ppm in the case of 0.8%, In the case of 1.6%, it is 150 ppm. From this, it can be seen that the lower the sulfate group concentration in the liquid deodorant, the better the deodorizing performance.
In the case of zero sulfate radical, commercially available iron nitrate containing no sulfate radical is used, and ferric hydroxide-containing hydrous sludge is not produced as an iron raw material. Although it is a reference example, in this case, the deodorization performance is the best, and it can be seen that the hydrogen sulfide generation amount is 500 ppm even immediately after the addition, and it is reduced to 50 ppm after 24 hours.

A deodorizer with a sulfate radical content of 2.4% is produced using ferric hydroxide-containing water-containing neutralized sludge containing 13.9 wt% (dry basis) of the sulfate radical described in Patent Document 2 as an iron raw material. However, the present invention does not fall under the scope of the present invention.
Although it is described in Table 4 for comparison with the liquid deodorant of the present invention, it is only a comparative example, and the liquid deodorant of the present invention is the above-mentioned patent at any sulfate group concentration. The deodorizing performance is superior to the deodorizing agent described in Document 2, and this is evident from the performance test results.

Since the liquid deodorizer of the present invention uses ferric hydroxide-containing water-containing neutralized sludge as an iron raw material, it contributes to the reduction of waste and effectively utilizes it.
In addition, in sewage and wastewater treatment facilities that generate high-concentration hydrogen sulfide, such as sludge storage tanks, or their ancillary facilities, they are extremely effective for suppressing or reducing the generation of hydrogen sulfide and can be utilized.

Claims (4)

Ferric-containing aqueous sludge hydroxide generated when neutralized iron compound-containing acidic waste liquid a liquid deodorant which is produced as a raw material, a second iron 7～35Wt% content in terms of Fe ₂ O ₃ And a malodor caused by the generation of hydrogen sulfide, wherein the NO ₃ / Fe molar ratio is in the range of 3.0 to 6.0 and the SO ₄ concentration is 1.6 wt% or less. Liquid deodorant. 9～20Wt% second iron calculated as Fe ₂ O _3, is in the range from NO ₃ / Fe molar ratio is 3.5, and sulfide of claim 1 SO ₄ concentration is less 0.8 wt% Liquid deodorant that suppresses bad odor caused by hydrogen generation . Nitric acid having a concentration of 20 wt% or more is mixed with ferric hydroxide-containing water-containing sludge generated when neutralizing the iron compound-containing acidic waste liquid at a NO ₃ / Fe molar ratio of 3.0 to 6.0, and the temperature The method for producing a liquid deodorant for suppressing malodor caused by the generation of hydrogen sulfide according to claim 1, wherein the solution is dissolved by heating at 60 to 100 ° C for 1 to 12 hours. Nitric acid with a concentration of 50 wt% or more is mixed with ferric hydroxide-containing water-containing sludge generated when neutralizing the iron compound-containing acidic waste liquid at a NO ₃ / Fe molar ratio of 3.5 to 5.5, and the temperature The method for producing a liquid deodorant for suppressing malodor caused by generation of hydrogen sulfide according to claim 3, wherein the dissolution is performed by heating at 75 to 100 ° C for 4 to 12 hours.